1. Field of the Invention
The present invention relates generally to network devices, and more particularly, to systems and methods for implementing virtual switch planes in physical switch fabrics of network devices.
2. Description of Related Art
Conventionally, high bandwidth switch fabrics have used several parallel switch “planes” that each carry a fraction of the total bandwidth. FIG. 1 illustrates a conventional switch fabric 100 with parallel switch planes 120, 125, 130 and 135. Each switch plane may include multiple interconnected switch integrated circuits (ICs) 110-1-110-12 (collectively, 110), with each switch IC employing one of a variety of switch architectures, such as a crossbar switch.
Interface cards 105 interconnect with switch ICs 110 of each of the parallel switch planes (only interconnections to switch plane 1 are shown) and divide the received bandwidth over the n planes of the switch fabric 100 (four planes shown). Each of interface cards 105 may interconnect with a number of ports on the switch ICs 110. If switch fabric 100 must support a total bandwidth B and have P ports, then each of the parallel switch planes must also have P ports, but each switch plane only needs to support a total bandwidth of B/n, where n is the number of planes. The use of parallel switch planes thus makes it possible for switch fabric 100 to support bandwidths much larger than could be supported by a single IC switch, without introducing much complexity.
The number of ports on a single switch plane, however, determines the most cost-effective number of interface cards 105 in a given system. Supporting small system sizes (i.e., smaller than the natural number of ports in a fabric) generally requires wasting ports, or designing a new switch fabric. Thus, a conventional switch fabric 100 cannot be used with systems having a different number of interface cards 105 than the number of ports on switch fabric 100.
Therefore, there exists a need for systems and methods that can enable a given switch fabric to support systems with fewer interface cards than the number of switch ports on the switch fabric, thus, permitting the implementation of smaller scale system sizes.